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1/******************************************************************************
2 * mcelog.c
3 * Driver for receiving and transferring machine check error information
4 *
5 * Copyright (c) 2012 Intel Corporation
6 * Author: Liu, Jinsong <[email protected]>
7 * Author: Jiang, Yunhong <[email protected]>
8 * Author: Ke, Liping <[email protected]>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License version 2
12 * as published by the Free Software Foundation; or, when distributed
13 * separately from the Linux kernel or incorporated into other
14 * software packages, subject to the following license:
15 *
16 * Permission is hereby granted, free of charge, to any person obtaining a copy
17 * of this source file (the "Software"), to deal in the Software without
18 * restriction, including without limitation the rights to use, copy, modify,
19 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
20 * and to permit persons to whom the Software is furnished to do so, subject to
21 * the following conditions:
22 *
23 * The above copyright notice and this permission notice shall be included in
24 * all copies or substantial portions of the Software.
25 *
26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
27 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
28 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
29 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
30 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
31 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
32 * IN THE SOFTWARE.
33 */
34
35#define pr_fmt(fmt) "xen_mcelog: " fmt
36
37#include <linux/init.h>
38#include <linux/types.h>
39#include <linux/kernel.h>
40#include <linux/slab.h>
41#include <linux/fs.h>
42#include <linux/device.h>
43#include <linux/miscdevice.h>
44#include <linux/uaccess.h>
45#include <linux/capability.h>
46#include <linux/poll.h>
47#include <linux/sched.h>
48
49#include <xen/interface/xen.h>
50#include <xen/events.h>
51#include <xen/interface/vcpu.h>
52#include <xen/xen.h>
53#include <asm/xen/hypercall.h>
54#include <asm/xen/hypervisor.h>
55
56static struct mc_info g_mi;
57static struct mcinfo_logical_cpu *g_physinfo __ro_after_init;
58static uint32_t ncpus __ro_after_init;
59
60static DEFINE_MUTEX(mcelog_lock);
61
62static struct xen_mce_log xen_mcelog = {
63 .signature = XEN_MCE_LOG_SIGNATURE,
64 .len = XEN_MCE_LOG_LEN,
65 .recordlen = sizeof(struct xen_mce),
66};
67
68static DEFINE_SPINLOCK(xen_mce_chrdev_state_lock);
69static int xen_mce_chrdev_open_count; /* #times opened */
70static int xen_mce_chrdev_open_exclu; /* already open exclusive? */
71
72static DECLARE_WAIT_QUEUE_HEAD(xen_mce_chrdev_wait);
73
74static int xen_mce_chrdev_open(struct inode *inode, struct file *file)
75{
76 spin_lock(&xen_mce_chrdev_state_lock);
77
78 if (xen_mce_chrdev_open_exclu ||
79 (xen_mce_chrdev_open_count && (file->f_flags & O_EXCL))) {
80 spin_unlock(&xen_mce_chrdev_state_lock);
81
82 return -EBUSY;
83 }
84
85 if (file->f_flags & O_EXCL)
86 xen_mce_chrdev_open_exclu = 1;
87 xen_mce_chrdev_open_count++;
88
89 spin_unlock(&xen_mce_chrdev_state_lock);
90
91 return nonseekable_open(inode, file);
92}
93
94static int xen_mce_chrdev_release(struct inode *inode, struct file *file)
95{
96 spin_lock(&xen_mce_chrdev_state_lock);
97
98 xen_mce_chrdev_open_count--;
99 xen_mce_chrdev_open_exclu = 0;
100
101 spin_unlock(&xen_mce_chrdev_state_lock);
102
103 return 0;
104}
105
106static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf,
107 size_t usize, loff_t *off)
108{
109 char __user *buf = ubuf;
110 unsigned num;
111 int i, err;
112
113 mutex_lock(&mcelog_lock);
114
115 num = xen_mcelog.next;
116
117 /* Only supports full reads right now */
118 err = -EINVAL;
119 if (*off != 0 || usize < XEN_MCE_LOG_LEN*sizeof(struct xen_mce))
120 goto out;
121
122 err = 0;
123 for (i = 0; i < num; i++) {
124 struct xen_mce *m = &xen_mcelog.entry[i];
125
126 err |= copy_to_user(buf, m, sizeof(*m));
127 buf += sizeof(*m);
128 }
129
130 memset(xen_mcelog.entry, 0, num * sizeof(struct xen_mce));
131 xen_mcelog.next = 0;
132
133 if (err)
134 err = -EFAULT;
135
136out:
137 mutex_unlock(&mcelog_lock);
138
139 return err ? err : buf - ubuf;
140}
141
142static __poll_t xen_mce_chrdev_poll(struct file *file, poll_table *wait)
143{
144 poll_wait(file, &xen_mce_chrdev_wait, wait);
145
146 if (xen_mcelog.next)
147 return EPOLLIN | EPOLLRDNORM;
148
149 return 0;
150}
151
152static long xen_mce_chrdev_ioctl(struct file *f, unsigned int cmd,
153 unsigned long arg)
154{
155 int __user *p = (int __user *)arg;
156
157 if (!capable(CAP_SYS_ADMIN))
158 return -EPERM;
159
160 switch (cmd) {
161 case MCE_GET_RECORD_LEN:
162 return put_user(sizeof(struct xen_mce), p);
163 case MCE_GET_LOG_LEN:
164 return put_user(XEN_MCE_LOG_LEN, p);
165 case MCE_GETCLEAR_FLAGS: {
166 unsigned flags;
167
168 flags = xchg(&xen_mcelog.flags, 0);
169
170 return put_user(flags, p);
171 }
172 default:
173 return -ENOTTY;
174 }
175}
176
177static const struct file_operations xen_mce_chrdev_ops = {
178 .open = xen_mce_chrdev_open,
179 .release = xen_mce_chrdev_release,
180 .read = xen_mce_chrdev_read,
181 .poll = xen_mce_chrdev_poll,
182 .unlocked_ioctl = xen_mce_chrdev_ioctl,
183};
184
185static struct miscdevice xen_mce_chrdev_device __ro_after_init = {
186 MISC_MCELOG_MINOR,
187 "mcelog",
188 &xen_mce_chrdev_ops,
189};
190
191/*
192 * Caller should hold the mcelog_lock
193 */
194static void xen_mce_log(struct xen_mce *mce)
195{
196 unsigned entry;
197
198 entry = xen_mcelog.next;
199
200 /*
201 * When the buffer fills up discard new entries.
202 * Assume that the earlier errors are the more
203 * interesting ones:
204 */
205 if (entry >= XEN_MCE_LOG_LEN) {
206 set_bit(XEN_MCE_OVERFLOW,
207 (unsigned long *)&xen_mcelog.flags);
208 return;
209 }
210
211 memcpy(xen_mcelog.entry + entry, mce, sizeof(struct xen_mce));
212
213 xen_mcelog.next++;
214}
215
216static int convert_log(struct mc_info *mi)
217{
218 struct mcinfo_common *mic;
219 struct mcinfo_global *mc_global;
220 struct mcinfo_bank *mc_bank;
221 struct xen_mce m;
222 unsigned int i, j;
223
224 mic = NULL;
225 x86_mcinfo_lookup(&mic, mi, MC_TYPE_GLOBAL);
226 if (unlikely(!mic)) {
227 pr_warn("Failed to find global error info\n");
228 return -ENODEV;
229 }
230
231 memset(&m, 0, sizeof(struct xen_mce));
232
233 mc_global = (struct mcinfo_global *)mic;
234 m.mcgstatus = mc_global->mc_gstatus;
235 m.apicid = mc_global->mc_apicid;
236
237 for (i = 0; i < ncpus; i++)
238 if (g_physinfo[i].mc_apicid == m.apicid)
239 break;
240 if (unlikely(i == ncpus)) {
241 pr_warn("Failed to match cpu with apicid %d\n", m.apicid);
242 return -ENODEV;
243 }
244
245 m.socketid = g_physinfo[i].mc_chipid;
246 m.cpu = m.extcpu = g_physinfo[i].mc_cpunr;
247 m.cpuvendor = (__u8)g_physinfo[i].mc_vendor;
248 for (j = 0; j < g_physinfo[i].mc_nmsrvals; ++j)
249 switch (g_physinfo[i].mc_msrvalues[j].reg) {
250 case MSR_IA32_MCG_CAP:
251 m.mcgcap = g_physinfo[i].mc_msrvalues[j].value;
252 break;
253
254 case MSR_PPIN:
255 case MSR_AMD_PPIN:
256 m.ppin = g_physinfo[i].mc_msrvalues[j].value;
257 break;
258 }
259
260 mic = NULL;
261 x86_mcinfo_lookup(&mic, mi, MC_TYPE_BANK);
262 if (unlikely(!mic)) {
263 pr_warn("Fail to find bank error info\n");
264 return -ENODEV;
265 }
266
267 do {
268 if ((!mic) || (mic->size == 0) ||
269 (mic->type != MC_TYPE_GLOBAL &&
270 mic->type != MC_TYPE_BANK &&
271 mic->type != MC_TYPE_EXTENDED &&
272 mic->type != MC_TYPE_RECOVERY))
273 break;
274
275 if (mic->type == MC_TYPE_BANK) {
276 mc_bank = (struct mcinfo_bank *)mic;
277 m.misc = mc_bank->mc_misc;
278 m.status = mc_bank->mc_status;
279 m.addr = mc_bank->mc_addr;
280 m.tsc = mc_bank->mc_tsc;
281 m.bank = mc_bank->mc_bank;
282 m.finished = 1;
283 /*log this record*/
284 xen_mce_log(&m);
285 }
286 mic = x86_mcinfo_next(mic);
287 } while (1);
288
289 return 0;
290}
291
292static int mc_queue_handle(uint32_t flags)
293{
294 struct xen_mc mc_op;
295 int ret = 0;
296
297 mc_op.cmd = XEN_MC_fetch;
298 set_xen_guest_handle(mc_op.u.mc_fetch.data, &g_mi);
299 do {
300 mc_op.u.mc_fetch.flags = flags;
301 ret = HYPERVISOR_mca(&mc_op);
302 if (ret) {
303 pr_err("Failed to fetch %surgent error log\n",
304 flags == XEN_MC_URGENT ? "" : "non");
305 break;
306 }
307
308 if (mc_op.u.mc_fetch.flags & XEN_MC_NODATA ||
309 mc_op.u.mc_fetch.flags & XEN_MC_FETCHFAILED)
310 break;
311 else {
312 ret = convert_log(&g_mi);
313 if (ret)
314 pr_warn("Failed to convert this error log, continue acking it anyway\n");
315
316 mc_op.u.mc_fetch.flags = flags | XEN_MC_ACK;
317 ret = HYPERVISOR_mca(&mc_op);
318 if (ret) {
319 pr_err("Failed to ack previous error log\n");
320 break;
321 }
322 }
323 } while (1);
324
325 return ret;
326}
327
328/* virq handler for machine check error info*/
329static void xen_mce_work_fn(struct work_struct *work)
330{
331 int err;
332
333 mutex_lock(&mcelog_lock);
334
335 /* urgent mc_info */
336 err = mc_queue_handle(XEN_MC_URGENT);
337 if (err)
338 pr_err("Failed to handle urgent mc_info queue, continue handling nonurgent mc_info queue anyway\n");
339
340 /* nonurgent mc_info */
341 err = mc_queue_handle(XEN_MC_NONURGENT);
342 if (err)
343 pr_err("Failed to handle nonurgent mc_info queue\n");
344
345 /* wake processes polling /dev/mcelog */
346 wake_up_interruptible(&xen_mce_chrdev_wait);
347
348 mutex_unlock(&mcelog_lock);
349}
350static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);
351
352static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
353{
354 schedule_work(&xen_mce_work);
355 return IRQ_HANDLED;
356}
357
358static int bind_virq_for_mce(void)
359{
360 int ret;
361 struct xen_mc mc_op;
362
363 memset(&mc_op, 0, sizeof(struct xen_mc));
364
365 /* Fetch physical CPU Numbers */
366 mc_op.cmd = XEN_MC_physcpuinfo;
367 set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
368 ret = HYPERVISOR_mca(&mc_op);
369 if (ret) {
370 pr_err("Failed to get CPU numbers\n");
371 return ret;
372 }
373
374 /* Fetch each CPU Physical Info for later reference*/
375 ncpus = mc_op.u.mc_physcpuinfo.ncpus;
376 g_physinfo = kzalloc_objs(struct mcinfo_logical_cpu, ncpus);
377 if (!g_physinfo)
378 return -ENOMEM;
379 set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
380 ret = HYPERVISOR_mca(&mc_op);
381 if (ret) {
382 pr_err("Failed to get CPU info\n");
383 kfree(g_physinfo);
384 return ret;
385 }
386
387 ret = bind_virq_to_irqhandler(VIRQ_MCA, 0,
388 xen_mce_interrupt, 0, "mce", NULL);
389 if (ret < 0) {
390 pr_err("Failed to bind virq\n");
391 kfree(g_physinfo);
392 return ret;
393 }
394
395 return 0;
396}
397
398static int __init xen_late_init_mcelog(void)
399{
400 int ret;
401
402 /* Only DOM0 is responsible for MCE logging */
403 if (!xen_initial_domain())
404 return -ENODEV;
405
406 /* register character device /dev/mcelog for xen mcelog */
407 ret = misc_register(&xen_mce_chrdev_device);
408 if (ret)
409 return ret;
410
411 ret = bind_virq_for_mce();
412 if (ret)
413 goto deregister;
414
415 pr_info("/dev/mcelog registered by Xen\n");
416
417 return 0;
418
419deregister:
420 misc_deregister(&xen_mce_chrdev_device);
421 return ret;
422}
423device_initcall(xen_late_init_mcelog);